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Two Cycling Off Modes in Pressure Support: Study of Respiratory Mechanics, Breathing Comfort and Asynchrony Patterns

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ClinicalTrials.gov Identifier: NCT00910286
Recruitment Status : Completed
First Posted : May 29, 2009
Last Update Posted : May 29, 2009
Sponsor:
Information provided by:
Hospital de Clinicas de Porto Alegre

May 28, 2009
May 29, 2009
May 29, 2009
December 2004
December 2007   (Final data collection date for primary outcome measure)
comfort [ Time Frame: 30 minutes ]
Same as current
No Changes Posted
Not Provided
Not Provided
Not Provided
Not Provided
 
Two Cycling Off Modes in Pressure Support: Study of Respiratory Mechanics, Breathing Comfort and Asynchrony Patterns
VENTILAÇÃO MECÂNICA COM PRESSÃO SUPORTE: ESTUDO DA ASSINCRONIA EXPIRATÓRIA (in Portughese)

Objective: To compare termination criteria (TC) of pressure support ventilation (PSV).

Design: Randomized cross-over clinical trial.

Setting: Intensive Care Units.

Patients: Sixteen patients on PSV with ability to answer a visual analog scale (VAS).

Protocol and Measurements: Each patient was ventilated with two different TC ventilators, fixed and automatic, with measurements of ventilatory mechanic variables, breathing comfort and asynchrony patterns.

Two ventilators with different flow termination criteria (TC) were compared: Servo 300 (Siemens-Elema, Solna, Sweden) with fixed TC (5% of peak inspiratory flow) and Newport E500 (Newport Medical Instruments, Costa Mesa, CA) with automatic TC (varies between 5% to 55%). Each patient remained three hours in the protocol, one hour in each ventilator, after been randomized to one of two sequences of 3 steps: Fixed 5% / Automatic / Fixed 5% or Automatic / Fixed 5% / Automatic (Figure 1). The transition among the ventilators was realized through a three-way flow directional valve (Three-Way T-Shape TM, Hans Rudolph Incorporation, Kansas City, EUA).

The PS level was determined by clinical staff to partially unload the respiratory muscle without respiratory distress based on observation of the patient's breathing pattern. The PS, the positive end expiratory pressure (PEEP), the inspiratory oxygen fraction (FiO2) and the pressure trigger sensitivity levels were unchanged during the protocol.

Study variables: Patients' demographic, anthropometric and clinical data were obtained (Table 1).

The study variables were detected noninvasively using only airway pressure (Paw) and flow signals, obtained with a pressure differential pneumotachometer (CO2SMO Plus; Novametrix Medical Systems, Wallingford, CT) located at the distal end of the ventilator circuit . Three records of five minutes were realized in each study step: time = 0' (0-5 min), t = 30' (30-35 min) and t = 55' (55-60 min). Data were digitalized at 100 Hz and recorded on a personal computer for subsequent analysis (LabVIEW 7.1, National Instruments Corporation, Austin, TX). A total of nine record phases of five minutes from each patient were analyzed .The variables values were obtained by one hundred ventilatory cycles from each recorded phase

Measured variables:

The following variables were analyzed (detailed descriptions of each one were in the Electronic Supplementary Material - ESM):

  • Ventilatory parameters: PS (PSadjusted); measured PS (PSeffective) and PEEP (PEEPeffective); peak airway pressure; effective flow termination criterion (TC - V'ti/V'peak, %) .
  • Breathing pattern: tidal volume obtained by mathematical integration of the flow signal; respiratory rate; minute ventilation; inspiratory time; expiratory time; duty cycle (Ti/Ttot); time constant obtained by measuring the slope off the expiratory limb of the flow-volume plot .
  • Respiratory effort: pressure-time product required to ventilator trigger (PTPtrigger) ; inspiratory delivered assistance pressure-time products at 300 ms (PTPdelivered-assistance300) and 500 ms (PTPdelivered-assistance500) after the onset of inspiratory effort; over assistance pressure-time product (PTPover-assistance) (see Figure 2 for details); airway occlusion pressure at 0.1 second (P0.1) .
  • Breathing comfort: evaluated by a modified VAS, labeled 0 to 10 (0 = best comfort and 10 = worst comfort) .
  • Asynchrony patterns: ineffective efforts, both during inspiration and expiration, (IEinspiratory and IEexpiratory), double-triggering (D-T) and autotriggering (A-T) were detected by visual inspection of the flow and airway pressure signals recordings .

Statistical Analysis:

The statistical analysis was performed using the Statistical Package for Social Science (SPSS 15.0, Chicago, EUA) and the significance level was established as p < 0.05. Tests are detailed in the ESM.

Interventional
Not Applicable
Intervention Model: Crossover Assignment
Masking: Single (Participant)
  • Ventilator Weaning
  • Respiration, Artificial
Other: Pulmonary Ventilator
The aim of the present study was to compare two different cycling off modes in PSV, a fixed and other automatic, about ventilatory mechanic variables, breathing comfort and patient-ventilator asynchrony patterns
Other Name: pressure support
VENTILATOR WEANING
Two ventilators with different flow termination criteria (TC) were compared: Servo 300 (Siemens-Elema, Sweden) with fixed TC (5% of peak inspiratory flow) and Newport E500 (Newport Medical Instruments, CA) with automatic TC (varies between 5% to 55%). Each patient remained three hours in the protocol, one hour in each ventilator, after been randomized to one of two sequences of 3 steps: Fixed 5% / Automatic / Fixed 5% or Automatic / Fixed 5% / Automatic . The PS, the positive end expiratory pressure (PEEP), the inspiratory oxygen fraction (FiO2) and the pressure trigger sensitivity levels were unchanged during the protocol.
Intervention: Other: Pulmonary Ventilator

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
18
Same as current
June 2008
December 2007   (Final data collection date for primary outcome measure)

Inclusion Criteria:

  • Patients under PSV for more than 24 hours,
  • Age > 18 years
  • Ability to answer to a symptom visual analog scale (VAS)

Exclusion Criteria:.

  • Hemodynamic instability (use of vasoactive drugs like dopamine, dobutamine or norepinephrine)
  • Bronchopleural fistula
Sexes Eligible for Study: All
18 Years and older   (Adult, Older Adult)
No
Contact information is only displayed when the study is recruiting subjects
Brazil
 
 
NCT00910286
Two cycling off modes in psv
No
Not Provided
Not Provided
josue almeida victorino, hospital mae deus
Hospital de Clinicas de Porto Alegre
Not Provided
Principal Investigator: josue a victorino, phd Hospital de Clinicas de Porto Alegre
Hospital de Clinicas de Porto Alegre
May 2009

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP